ELDORET, Kenya—One cold morning in April, as Esleen Rotich walked up a dirt road that led to the manicured lawns of Equator Flowers farm, she could sense that something was off. On ordinary mornings, when she would arrive for her 7:20 a.m. shift, the farm was usually silent as employees worked quietly at their stations. But this morning, she heard chattering voices. She also noticed her colleagues huddled near a pit…..